The value of fetal magnetic resonance imaging in diagnosis of congenital anomalies of the fetal body: a systematic review and meta-analysis.

OBJECTIVES: To undertake a systematic review to assess the accuracy of fetal MRI in diagnosis of non-CNS congenital anomalies of the fetal body in comparison with antenatal ultrasound when correlated to postnatal diagnosis. METHODS: Searches were conducted from electronic databases, key journals and reference lists for eligible papers. Inclusion criteria was original research studies comparing the diagnostic results of antenatal ultrasound, fetal MRI and final postnatal diagnosis via imaging, surgery or post-mortem testing. Studies of CNS anomalies were excluded. Studies were assessed for risk of bias by two reviewers working independently and data was then extracted by a single reviewer. RESULTS: 12 studies were included with a total of 361 eligible patients who underwent USS and MRI and had a postnatal diagnosis. USS alone had a diagnostic accuracy of 60.6% whereas MRI had an improved diagnostic accuracy of 86.4%. The overall odds ratio was 0.86 (CI 0.202-1.519 and p-value < 0.01). CONCLUSION: Fetal MRI makes a significant contribution to accurate diagnosis of congenital abnormalities of the fetal body; especially in genito-urinary anomalies. More research is needed to improve the evidence base for the role of fetal MRI in diagnosis of congenital anomalies in other body systems.

Robert's uterus (asymmetric septate uterus): a rare congenital Müllerian duct anomaly.

Müllerian anomalies such as Robert's uterus, which was first described by the French gynaecologist Dr Helene Robert in 1969, are rare clinical entities and have been reported in <3% of the female population. Robert's uterus is a rare phenomenon with a relative dearth of reported cases. Affected individuals may present with pelvic pain and dysmenorrhoea that intensifies near menses or acutely, with severe abdominal pain to the emergency department. They are also associated with adverse pregnancy outcomes, abnormal fetal presentation, preterm labour, recurrent pregnancy loss and infertility. Although ultrasound has a role in its initial assessment, MRI is the best modality to further delineate its anatomy. It is typically managed via laparotomy and total horn resection, endometrectomy of the blind cavity or abdominal metroplasty. The authors present the case of a 40-year-old woman at 19+3 weeks gestation with acute onset of left-sided abdominal pain. A transvaginal ultrasound and MRI of the pelvis confirmed a Robert's uterus with a viable pregnancy in the upper left horn. She developed a ruptured horn with significant haemoperitoneum. An emergency laparotomy was performed and a non-viable fetus was evident. Only a few cases of pregnancy in the blind hemicavity have been reported so far. This case also highlights the importance of considering this diagnosis in young females presenting with dysmenorrhoea and normal menstrual flow. It is imperative to render a prompt diagnosis, as minimally invasive procedures may be more effective if detected before the formation of adnexal endometriomas.

Benefits and Limitations of the Minimally Invasive Postmortem: A Review of an Innovative Service Development.

INTRODUCTION: Pediatric postmortem (PM) rates have significantly declined, creating a need for effective minimally invasive alternatives to correlate with parental wishes. We review the use of a minimally invasive fetal and neonatal PM service further to preliminary findings published in 2015. MATERIALS AND METHODS: Cases taken from the mortuary electronic database from 2012 to 2017 are analyzed. The minimally invasive service consisted primarily of external examination, magnetic resonance imaging (MRI), and placental examination. Any significant conditions found noted. All pathology reports include a Relevant Condition at Death (ReCoDe) obstetric classification. Reports analyzed to determine which aspects of the service provided positive information. RESULTS: Of 1498 perinatal postmortems, 105 (7%) were PM MRI, of which 75.24% were intrauterine fetal deaths. Relevant conditions were identified in 94 cases (89.52%), and ReCoDe categories in 80 cases (76.19%). Moreover, 90% of cases had a ReCoDe condition, with 10% unclassified. Seven cases had more than 1 ReCoDe. Main conditions related to placenta (32.5%) and umbilical cord (27.5%). The most informative elements were placental examination and MRI. CONCLUSION: Minimally invasive PMs are a viable alternative to traditional autopsy when this option is refused. However, further case analysis is needed to determine potential bias toward certain classification codes.

ESPR postmortem imaging task force: where we begin.

A new task force on postmortem imaging was established at the annual meeting of the European Society of Paediatric Radiology (ESPR) in Graz, Austria, in 2015. The postmortem task force is separate from the child abuse task force as it covers all aspects of fetal, neonatal and non-forensic postmortem imaging. The main focus of the task force is the guidance and standardization of non-radiographic postmortem imaging, particularly postmortem CT and postmortem MRI. This manuscript outlines the starting point of the task force, with a mission statement, outline of current experience, and short- and long-term goals.

Initial experiences of a minimally invasive autopsy service. A report of the techniques and observations in the first 11 cases.

Our goal was to set up a clinical service for minimally invasive postmortem examination for the fetal and neonatal age group. The minimally invasive service consisted of imaging, external review, placental examination, and ancillary tests that form part of the formal autopsy process. Eleven patients had imaging and relevant conditions at death successfully determined with the minimally invasive service. We conclude that a minimally invasive autopsy service for fetal and neonatal cases is possible and acceptable to patients and professionals.

Recurrent pseudo-TORCH appearances of the brain presenting as "Dandy-Walker" malformation.

Dandy-Walker malformation (DWM) is a developmental abnormality characterized by cystic dilatation of the fourth ventricle, complete or partial agenesis of the cerebellar vermis, and enlarged posterior fossa with upward displacement of the lateral sinuses, tentorium, and torcula. Calcification of brain tissue is a feature of congenital infection, particularly those involving the TORCH ( Toxoplasma gondii , rubella virus, Cytomegalovirus, and herpesvirus) group. An autosomal-recessive congenital infection-like syndrome with intracranial and extracranial calcifications has been categorized as pseudo-TORCH syndrome. We describe two male siblings diagnosed as DWM by ultrasound and by in utero and postmortem magnetic resonance imaging (MRI) but in whom the neuropathology revealed features of intracranial necrosis and calcification in the absence of extracranial calcific deposition. The fetal anomaly was identified by routine prenatal ultrasound scan at 16 weeks. In both cases the postmortem MRI showed bilateral ventriculomegaly with distortion of the overlying cortices, enlarged posterior fossa with a cyst related to small cerebellar hemispheres, and an incomplete cerebellar vermis. The diagnosis of DWM was offered. The histology revealed hypoplastic cerebral hemispheres with poorly cellular developing cortex. The white matter and periventricular matrix were disrupted by areas of necrosis and calcification not associated with any inflammatory infiltration, organisms, inclusions, or giant cells. To our knowledge, these two male siblings are the 1st cases that show pseudo-TORCH syndrome with distinctive intracranial calcification presenting as DWM. An autosomal-recessive or X-linked inheritance needs to be considered. Our study confirms the relevance of the multidisciplinary teamwork involved in the diagnosis of these complex cases.

Is there a causal relationship between open spinal dysraphism and Chiari II deformity? A study using in utero magnetic resonance imaging of the fetus.

BACKGROUND: Chiari II deformity is associated with open spinal dysraphism. A causal relationship has been proposed by McLone and Knepper. This article evaluates that hypothesis. OBJECTIVE: To establish the frequency of Chiari II deformity in fetuses with open spinal dysraphism, assess whether meningocele sac neck area and volume influence the severity of posterior fossa changes, and assess whether the severity of associated findings (ventriculomegaly, amount of extracerebral CSF) are associated with Chiari II deformity. METHODS: Sixty-five fetuses with open spinal dysraphism were compared with gestationally aged matched "normal" fetuses on ultrafast MR images. Cerebellar vermis and bony posterior fossa surface area were measured on midline sagittal images. Hindbrain herniation was noted if present. In the open spinal dysraphic group, sac neck area and volume were measured. Ventriculomegaly was assessed by linear measurement of the trigone of the lateral ventricle and extracerebral CSF depth was measured maximally over the lateral surface of the cerebral hemispheres. RESULTS: Fifteen of 65 fetuses with open spinal dysraphism did not have Chiari II deformity. Neck area and volume of the sac did not correlate with the presence of Chiari II deformity or reduction in bony posterior fossa size. CONCLUSION: A relatively high proportion of fetuses with open spinal dysraphism do not have Chiari II deformity in utero. There is a lack of correlation between indicators of spinal dysraphism severity and the extent of the posterior fossa abnormality. This raises some interesting questions about the causality of the Chiari II deformity.

Magnetic resonance imaging of the fetus.

Fetal magnetic resonance imaging (MRI) has become established as part of clinical practice in many centres worldwide especially when visualization of the central nervous system pathology is required. In this review we summarize the recent literature and provide an overview of fetal development and the commonly encountered fetal pathologies visualized with MRI and illustrated with numerous MR images. We aim to convey the role of fetal MRI in clinical practice and its value as an additional investigation alongside ultrasound yet emphasize the need for caution when interpreting fetal MR images especially where experience is limited.

Neonatal cochlear function: measurement after exposure to acoustic noise during in utero MR imaging.

PURPOSE: To establish whether fetal exposure to the operating noise of 1.5-T magnetic resonance (MR) imaging is associated with cochlear injury and subsequent hearing loss in neonates. MATERIALS AND METHODS: The study was performed with local research ethics committee approval and written informed parental consent. Neonatal hearing test results, including otoacoustic emission (OAE) data, were sought for all neonates delivered in Sheffield who had previously undergone in utero MR imaging between August 1999 and September 2007. The prevalence of hearing impairment in these neonates was determined, with corresponding 95% confidence intervals calculated by using the binomial exact method, and mean OAE measurements were compared with anonymized local audiometric reference data by using the t test. RESULTS: One hundred three neonates who had undergone in utero MR imaging were identified; 96 of them had completed hearing screening assessment. Thirty-four of these babies were admitted to the neonatal intensive care unit (NICU), and one of them had bilateral hearing impairment. The prevalence of hearing impairment was 1% (one of 96; 95% confidence interval: 0.03%, 5.67%), which is in accordance with the prevalence expected, given the high proportion of babies in this study who had been in the NICU (ie, NICU graduates). In addition, for the well babies, there was no significant difference in mean OAE cochlear response compared with that for a reference data set of more than 16,000 OAE results. When NICU graduates were included in the comparison, a significant difference (P = .002) was found in one of four frequency bands used to analyze the cochlear response; however, this difference was small compared with the normal variation in OAE measurements. CONCLUSION: The findings in this study provide some evidence that exposure of the fetus to 1.5-T MR imaging during the second and third trimesters of pregnancy is not associated with an increased risk of substantial neonatal hearing impairment.

Subdural hemorrhage, intradural hemorrhage and hypoxia in the pediatric and perinatal post mortem: are they related? An observational study combining the use of post mortem pathology and magnetic resonance imaging.

BACKGROUND AND PURPOSE: Controversies exist over the causes of intradural hemorrhages (IDH), subdural hemorrhages (SDH) and hypoxia. SDH is a recognised finding at perinatal and pediatric autopsy. We describe the occurrence of IDH, SDH, and hypoxia in these deaths using a combined approach of post mortem magnetic resonance imaging (PM MRI), autopsy examination and histology. MATERIAL AND METHODS: Forty-two cases (1 day to 4 years, mean 6.9 months) underwent PM MRI and autopsy. Two further children (8 and 32 month of age) underwent autopsy only. MRI was conducted with a 1.5 T Magnet with fast spin-echo T2 weighted images, the images were assessed for the presence of SDH, hypoxia and structural abnormalities. Hypoxia was defined by a low signal in the ventrolateral thalami and peri-rolandic regions on MRI. Edema was interpreted as early acute hypoxia. On histology, hypoxia was defined by the presence of hypoxic neurons. RESULTS: IDH was seen histologically in 35/39 cases: diffuse in 17 and focal in 18. On the PM MRI focal IDH was not distinguished, and DIDH was only retrospectively suggested as a low signal around the venous sinuses or prominent venous sinuses, predominantly in the posterior falx and tentorium. Confident identification on the MRI was not possible. 12/17 cases with DIDH were less than a week old. SDH was seen in 11 cases on PM MRI. SDH was seen at autopsy in the same 11 cases and in the 2 cases where no PM MRI was performed. DIDH was seen in all these cases on histological examination (except in 1 case where the dura had not been sampled). Acute hypoxia was present in 14/42 cases both on histology and MRI. In 1 case changes of hypoxia were seen on MRI only. In 7 cases the hypoxia was seen on histology only. 12/13 cases with SDH had features of hypoxia. Of the cases with DIDH on histology 14/17 had hypoxia (on MRI, histology, or both). CONCLUSION: IDH and SDH are frequent findings in the perinatal and pediatric autopsy. SDH was associated with a DIDH and was also frequently associated with hypoxia. Focal IDH was not identified at the PM MRI; it was associated with hypoxia (on MRI and/or on histology) in less than a quarter of cases. Our results exhibit an association between IDH, SDH and hypoxia in children dying of natural causes. The highest incidence is seen in the perinatal period.

Appearances of diffuse excessive high signal intensity (DEHSI) on MR imaging following preterm birth.

BACKGROUND: Diffuse damage to the periventricular white matter has recently been suggested to be a cause of the cognitive deficits seen following preterm birth. It is unclear whether this form of injury can be visualised on MR imaging, but one group has described diffuse excessive high signal intensity (DEHSI) as a possible form of diffuse white matter injury. This finding is dependent on window imaging and the subjective assessment of the reviewer, but little data have been published on the degree of subjectivity on its appearance among raters. OBJECTIVE: To assess the subjectivity of DEHSI on conventional and ultrafast T2-weighted MR imaging following preterm birth. MATERIALS AND METHODS: An observational study of 40 preterm infants who had MR imaging of the brain around term-equivalent age, including conventional fast spin-echo (FSE) and ultrafast single-shot fast spin-echo (SSFSE) T2-weighted sequences in the axial plane. Images were anonymised and scored twice by four observers for the presence of DEHSI. Inter- and intra-observer agreement were calculated. RESULTS: Sixty-five percent of conventional and 100% of the ultrafast images were of diagnostic quality. DEHSI was noted in between 0% and 69.2% of conventional images and 27.5-90% of the ultrafast images. Inter- and intra-observer agreement ranged from none to moderate. CONCLUSION: The visual appearances of DEHSI on conventional FSE and ultrafast SSFSE T2-W images are highly subjective, limiting its clinical application.

Diffusion-weighted imaging of cerebral white matter and the cerebellum following preterm birth.

AIM: The aim of this study was to determine if apparent diffusion coefficients (ADCs) generated with diffusion-weighted imaging of cerebral white matter and the cerebellum are affected by white matter damage. METHOD: Seventy-two preterm infants (32 males, 40 females; mean gestational age at birth 30.3 wks, SD 3.0 wks; mean birthweight 1458g, SD 534g) underwent magnetic resonance imaging of the brain around term-equivalent age and were categorized into three groups: normal, overt abnormality, and diffuse excessive high signal intensity (DEHSI). ADC values were calculated from cerebral white matter, cerebellar hemispheres, and cerebellar midline, and were compared between groups. Regression analysis identified clinical parameters correlated with ADC values. RESULTS: Imaging was normal in 27 infants, and revealed overt abnormalities in 14 and DEHSI in 31. ADC values did not differ between groups. ADC values from cerebral white matter were negatively correlated with the number of episodes of postnatal sepsis (p=0.002). ADC values from cerebellar hemispheres (p=0.007) and cerebellar midline (p=0.036) correlated with gestational age at birth. INTERPRETATION: ADC values from white matter are not altered in preterm infants with DEHSI but are negatively correlated with the number of episodes of postnatal sepsis. ADC values in the cerebellum are not altered by white matter damage, but are affected by preterm birth itself.

Cranial vault defects: the description of three cases that illustrate a spectrum of anomalies.

Three cases of cranial vault defects in fetuses are described. All 3 cases underwent postmortem examination, and in 2 of them postmortem magnetic resonance imaging was also performed. The phenotypical differences between the cases illustrate a spectrum of cranial vault defects, associated anomalies, and pathogenic mechanisms involved in the etiology of this rare malformation. All 3 cases were male, and the cranial vault defects corresponded to exencephaly with acrania/acalvaria caused by amniotic band syndrome, acalvaria, and acrania presenting in a chorangiopagus parasiticus twin.

Less invasive autopsy: benefits and limitations of the use of magnetic resonance imaging in the perinatal postmortem.

The decline in the postmortem (PM) autopsy rate in the United Kingdom paralleled the change in public perception of this procedure after the organ retention crisis in 2000. The introduction of magnetic resonance imaging (MRI) in the fetal, perinatal, and pediatric autopsy led some investigators to propose that MRI could replace the conventional PM. We assessed the role of MRI in fetal autopsy as an addition or a potential replacement method to the conventional PM and to evaluate the benefits and limitations of each technique. We retrospectively reviewed the PM and MRI examination of 100 fetuses. The MRI was limited to the brain or brain and spinal cord. Forty-six cases involved termination of pregnancy; 30 were intrauterine fetal deaths/stillbirths; 16 were premature deliveries followed by neonatal death; and 8 were miscarriages. The mean gestational age of all cases was 25.54 weeks (range: 13-41 weeks). In 54 of the 90 full PMs, there was a complete agreement between the MRI and autopsy findings on the morphology of the brain and spine. Despite this agreement, the information gained at the PM was relevant to find the cause or mechanism of death in 20 of 54 cases (37%). In 24 autopsies the MRI added valuable information to the autopsy. However, if MRI had been the only investigation, essential information would have been lost in 17 of 24 cases (71%). In 12 cases the PM was clearly superior to the MRI. The integrated result obtained from the traditional autopsy remains crucial in determining the cause or mechanism of the malformation or of the fetal/perinatal death and accordingly is important for the counseling offered to parents regarding the recurrence risk for future pregnancies.

SNR phase order k-space encoding (SPOKE).

A method of determining the phase-encode order for MR Fourier-encoded imaging is described, which provides an additional option for optimizing images from samples with signals that change during data acquisition. Examples are in hyperpolarized helium gas imaging of the lungs where polarization is lost with each RF pulse or the signal changes observed in rapid dynamic studies with T(1) or T(2)* contrast agents when mixing is taking place. The method uses a single frequency-encoded projection in the proposed phase-encoding direction. The projection is subsequently sorted into signal-to-noise ratio (SNR) order. The indices of the sorted array are then used to create the phase-encode table to be used for the scan. This phase table is sorted in descending SNR order for signals that decrease during data acquisition and in ascending order for signals that increase during data acquisition. Simulations suggest that this technique can produce higher resolution than centric-ordered phase encoding at the expense of increased modulation (ghosting) artifact for dynamically changing signals. Initial practical implementation of the technique has been carried out on a dedicated 0.2-T Niche MR system, and the test object results agree well with simulations. Hyperpolarized 3-He lung images have also been acquired and postprocessed using the SNR phase order k-space encoding (SPOKE) methodology and show potential for improved imaging with high flip angles where polarization is rapidly lost. Applications may also be found for 3D volumetric acquisitions where two dimensions can be SPOKE encoded.

Measuring hip development using magnetic resonance imaging.

BACKGROUND: Abnormal hip development can have severe consequences if not detected and treated early. Previous studies have shown that if the abnormality is detected early, the outcome is good. Much is known about embryological hip development (weeks 1-10 after conception) from postmortem examination. For ethical reasons, information about hip development in the fetal stage of pregnancy (10 weeks to term) is less certain as it is largely gained from animal studies and from early radiograph studies. A few autopsy-based studies have been reported looking at hip development, but no one has shown, to our knowledge, that postmortem magnetic resonance is able to provide the same and possibly more information. The aim of this study was to assess the value of magnetic resonance imaging in providing information on fetal hip development. METHODS: Measurements of 30 patients (gestation, 17-42 weeks) were made regarding the width and depth of the acetabulum and the radius and diameter of the femoral head; volume and area were calculated. RESULTS: With the exception of the acetabular width, each dimension showed little development until week 20 when growth rose exponentially. The acetabular width showed a slow rate of growth, despite changes in the femoral head. Levels of observer agreement were high for all but depth (intraclass correlation coefficients, 0.90). CONCLUSIONS: The measurements were in line with previous postmortem studies. Magnetic resonance imaging is a valid alternative to postmortem in the assessment of hip development. Magnetic resonance imaging has the potential to alert clinicians to the possible abnormal development, allowing early intervention. STUDY DESIGN: Cross-sectional study with purposive sampling.

Imaging the fetal spine using in utero MR: diagnostic accuracy and impact on management.

BACKGROUND: In-utero MR imaging (iuMR) has entered the clinical arena during the last decade. It is used mainly for imaging fetal brain abnormalities. OBJECTIVE: To report our experience of imaging the fetal spine and spinal cord in fetuses with known or suspected abnormalities diagnosed on US imaging. MATERIALS AND METHODS: Prospective imaging and retrospective analysis of the possible impact on management of 50 consecutive fetuses with spinal abnormalities detected by antenatal US imaging. RESULTS: In 40 (80%) of 50 fetuses, iuMR and US imaging were in complete agreement. In the other 10 fetuses (20%), iuMR provided additional information or changed the diagnosis, including 8 fetuses where the iuMR could find no abnormality and was found to be correct by later follow-up. CONCLUSION: IuMR is useful in fetuses with a suspected spinal abnormality. The clinical impact of iuMR may be numerically less than with brain abnormalities, but is still sufficient to warrant its use, especially if there is any uncertainty about the US imaging, and particularly as a relatively high proportion of diagnoses on US imaging are false-positives.

Simultaneous parallel inclined readout image technique.

Sensitivity-encoded phase undersampling has been combined with simultaneous slice excitation to produce a parallel MRI method with a high volumetric acquisition acceleration factor without the need for auxiliary stepped field coils. Dual-slice excitation was produced by modulating both spin and gradient echo sequences at +/-6 kHz. Frequency aliasing of simultaneously excited slices was prevented by using an additional gradient applied along the slice axis during data acquisition. Data were acquired using a four-channel receiver array and x4 sensitivity encoding on a 1.5 T MR system. The simultaneous parallel inclined readout image technique has been successfully demonstrated in both phantoms and volunteers. A multiplicative image acquisition acceleration factor of up to x8 was achieved. Image SNR and resolution was dependent on the ratio of the readout gradient to the additional slice gradient. A ratio of approximately 2:1 produced acceptable image quality. Use of RF pulses with additional excitation bands should enable the technique to be extended to volumetric acquisition acceleration factors in the range of x16-24 without the SNR limitations of pure partially parallel phase reduction methods.